This invention relates to a sheet-metal nut for blind fastening a screw in a hole in a carrier plate. The sheet-metal nut includes a top plate that bears against the front side of the carrier plate adjacent a hole in the carrier plate and having a cutout for the passage of a screw and a threaded sleeve spaced from the top plate that is connected to the top plate by connecting webs that fold outwardly when a screw is threaded into the sleeve.
Sheet-metal nuts of this type have the advantage that, after inserting the threaded sleeve into the hole in the carrier plate, the connecting webs, when the screw is screwed into the sleeve pulling it towards the carrier plate, fold outwardly and are brought to bear firmly against the rear side of the carrier plate adjacent the edge of the hole. The sheet-metal nut is thus anchored securely in the carrier plate with a large retaining force.
British patent No. 438,011 discloses a sheet-metal nut of this type, in which the top plate having connecting webs projecting from six sides is punched out of a single blank. The connecting webs are bent over, approximately at right angles and, at their ends, are connected to a separate nut which is provided with a peripheral groove to receive the ends of the webs. Owing to the ray-like arrangement of the connecting webs, the sheet-metal nut requires, for its production, a relatively wide strip of sheet-metal and there is also a comparatively large amount of waste after the nut has been punched from it. Moreover, since a special, non-standard nut is used, which nut has to be mounted in a special procedure, the known sheet-metal nut is very expensive to manufacture as a mass-produced item.
The object of the invention therefore is to design a sheet-metal nut that can be shaped in a substantially simpler manner, without impairing its retaining force, and is also cheaper to produce.